cepheus-navis 5.12.15

Airgapped Tableau-to-Power BI conversion tool with proven calculation correctness and signed governance artifacts

Cepheus Navis

Airgapped Tableau-to-Power BI conversion tool where every calculation translation is backed by a mathematical proof of correctness — the conversion is demonstrably correct, not just plausible.

Cepheus Navis reads a Tableau workbook (.twb / .twbx) and writes a Power BI Project (.pbip) — without connecting to any database or network. Signed audit trails, equivalence reports, and pre-conversion analysis are delivered as tamper-evident PDFs.

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Key capabilities

Capability	Details
Airgapped operation	Core conversion runs with no network access; structure is migrated, not data
Proven calculation correctness	Every DAX formula is tested against actual Tableau output — proven equivalence, not approximate translation
Pre-conversion analysis	Analysis report shows automation rate, complexity ratings, and degradation summary per workbook — before you convert
Signed audit trails	Per-calculation translation records with original formulas and DAX equivalents — tamper-evident PDFs with embedded JSON
Calculation coverage	Aggregations, LOD expressions (FIXED, INCLUDE, EXCLUDE), table calculations, IF/CASE/IIF, string/date/math functions
Consult mode	Assess an existing Power BI conversion (from any source) against Navis's validated reference — per-calculation verdicts without exposing reference DAX
Filter migration	Categorical, range, date, and Top N filters translated to Power BI equivalents
Data model	Tables, columns, and data types emitted as TMDL semantic model definitions
Visual types	Bar, line, area, pie, scatter, map, table, and more

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Requirements

• Python 3.9 or later
• A licensed Cepheus Navis installation (see Licensing below)

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Installation

pip install cepheus-navis

Verify the installation:

cepheus-navis --version

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Quick start

Every command takes a spec.toml project file as its first argument. Create one for your project and fill in the paths. CLI flags override spec values when provided.

1. Analyze your workbooks

cepheus-navis analyze spec.toml

Scans the directory for Tableau workbooks and produces a License Request PDF — automation rate, per-workbook complexity ratings, degradation summary, and SHA-256 checksums. Submit it to [e-mail] to obtain a license file.

2. Verify your license

Add the license path to your spec.toml:

[verify-license]
license_file = "license.json"
path = "C:/Tableau/Workbooks"

Then verify:

cepheus-navis verify-license spec.toml

The output shows VALID, MISMATCH, or UNLICENSED for each workbook. If a file shows MISMATCH, it was modified since analysis — re-run analyze and request a new license.

3. Convert

cepheus-navis convert spec.toml

4. Consult — assess an existing conversion

Already have a Power BI conversion from another tool or hand-coded? Compare it against Navis's validated reference. Requires a consult licence.

Add the consult section to your spec.toml:

[consult]
path    = "C:/Tableau/Workbooks/Sales.twbx"
against = "C:/PowerBI/SalesProject.pbip"
output  = "C:/Reports/consult-output"

Then run:

cepheus-navis consult spec.toml

The Consult Report tells you which of your DAX calculations are correct, which have structural issues, and which Tableau calculations are missing from your project — assessed against a proven reference. Requires a PBIP project folder — .pbix files must be saved as Power BI Projects first.

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What to expect

Navis provides verified semantic equivalence for calculations, data structures, and data model elements. Confidence levels (Exact, Composed, Deterministic, Degraded) are documented in the Conversion Evidence Capsule.

Dashboard layout and chart types are converted on a best-effort basis. Visual formatting — colours, fonts, padding, reference lines, tooltips, conditional formatting, etc. — requires human review and adjustment in Power BI Desktop.

Calculations: verified. Visuals: best-effort, human review required.

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Output structure

SalesDashboard/
├── SalesDashboard.pbip                # Entry point
├── SalesDashboard.Report/
│   ├── definition.pbir
│   └── report.json
├── SalesDashboard.SemanticModel/
│   ├── definition.pbism
│   └── definition/
│       ├── model.tmdl
│       ├── database.tmdl
│       ├── tables/
│       │   └── Orders.tmdl            # Your measures (DAX) live here
│       └── cultures/
│           └── en-US.tmdl
└── SalesDashboard_CEC.zip             # Evidence Capsule (see below)

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Licensing

Cepheus Navis uses a checksum-based license that ties a specific license file to specific workbook files.

analyze  →  submit report  →  receive license  →  convert

The analyze command produces a PDF containing SHA-256 checksums of your workbooks. Cepheus issues a license that approves exactly those files. The convert command validates the checksums before running the pipeline. This prevents accidental conversion of modified or untested workbooks.

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Governance artifacts

Two signed artifacts are produced by the convert command. They cannot be disabled.

Conversion Report PDF — produced for each workbook:

• Every calculation with its original Tableau formula and converted DAX
• Worksheet-to-page mapping with visual type translations
• Degradation addendum listing features that need manual attention
• Data model summary (tables, columns, data types)

Evidence Capsule (_CEC.zip) — tamper-evident conversion record:

• The conversion report PDF
• Original workbook and generated Power BI project files
• Machine-readable audit log of every step the tool took
• Cryptographic hash chain linking inputs → outputs → proofs → audit records

All PDFs are tamper-evident with embedded JSON attachments and integrity signatures.

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Further reading

The complete How-To Guide is bundled with the package. After installation:

cepheus-navis howto

This opens the full guide in your browser — installation, spec.toml configuration, the three-step workflow, governance artifacts, digital signing, audit logs, and troubleshooting. Works offline.